On Friday, the Atlanta-based shipping giant said it continued to deliver packages delayed by what it acknowledged late Tuesday was volume exceeding its network capacity.

There were many factors likely at play, spokeswoman Natalie Black said in an interview. For one, she said, the company was affected by “severe weather” in the Dallas area. Plus, this holiday season comprised six fewer days between Thanksgiving and Christmas this year, she said. Meanwhile, she said, packages that arrived at the company’s own Worldport air hub in Louisville, Ky., on Monday for next-day air delivery exceeded UPS’s internal forcast.

She declined to specify the number of packages affected but said UPS had forecast more than 7.75 million domestic air packages on the peak day, Dec. 23, including more than 3 million packages passing through the hub.

“There’s no hard fast answer as to where the disconnect was,” she said. “There are so many factors. We have our own historical data. We mine data from retailers. Our projections were off. We exceeded capacity.”

Black said its airport hub in Louisville operates 2,400 daily flights, with an additional 23 cargo planes in use for the holiday peak weeks, compared with about 950 daily flights on an average day.

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